And raymond m



UNITED STATES PATENT OFFICE.

JOSEPH I-I. WEEKS, RUTLEDGE, PENNSYLVANIA, ASSIGNOR TO JACKSON S. WEEKS,

OF DELAWARE COUNTY, PENNSYLVANIA, AND

PHIA, PENNSYLVANIA, TRUSTEES.

RAYMOND M. WEEKS, OF PHILADEL- COMPOSI'IION FOR ELECTROLYTES FORELECTRICAL ETCHIN G.

' No Drawing.

To all whom it ma concern:

Be it known t at I, JOSEPH H. WEEKS, a citizen of the UnitedStates,residing at Rutledge, in the county of Delaware and State ofPennsylvania, have invented certain new and useful Improvements inComposition for Electrolytes for Electrical Etching, of which thefollowing is a specifica- I have described and claimed certain im provedapparatus. The electrolyte which 1 shall hereinafter set forth isadapted for use in the aforesaid processes, and with theaforesaidapparatus, although it is not necessarily limited thereto,'and may beemployed in other connections, and for other metals or alloys of metalsthan those therein specifically described.

In the prior applications referred to, I have set forth a method ofetching plates in which a resistant image is produced on a plate, eitherby means of ink or powder, which is well known in the art, or by meansof a special gelatin albumen enamel of my @own invention. The plate soprepared is suspended in a suitable bath or solution and.

connected so as to form the anode terminal of a circuit supplied withcurrent of suitable voltage to produce the desired amperage or volume ofcurrent flow per unit area of the anode. The cathode terminal, which isalso immersed in the bath or solution, may be of various types and ofvarious materials. In my application I have described carbon cathodes,and have set forth means for keeping the surface of the plate clean sothat it shall be completely and uniformly exposed to the electrolyticaction of Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed April 30, 1917. Serial Ito/165,476. I

the current, and for keeping the cathodes clean, and for preventingundercuttin of the edges of the image or lines on the p ate.

The problems to be met are different from those presented in theelectro-plating art because, in the latter, it is-the depositlon ofmetal which concerns the operator, and which must be even and regular,as well as reasonably rapid; whereas, in the present cases, it is theremoval of the metal by the current into or through the solution, whichmust be properly regulated,and this to a niuch greater degree ofaccuracy and uniformity than is necessary in the art of deposition.

In my experimental work, which has ex tended over a considerable period,and in the course of which the present invention and the othershereinbefore referred to have been produced, I have found that thecomposition of the electrolyte plays a very considerable part, not onlyin the regulation of the action on the plate, but in the uniformity ofsuch action, and in maintainin said uniformity for any appreciable perod of time.

Without going into detail at this time, into the chemical reactions orthe steps in transference of the metals, which take place with anyparticular composition, I may say generally that I have found itnecessary to provide a solution which shall have, first the properconductivity; second, a capacityfor absorbing and transferring theelectr1-' cally displaced metal from the plate without soon becomingsaturated or clogged; third, no tendency to foul or coat or form bubblesor spots upon the pl te, which would impede the free passageof hecurrent and thereby mar the engraving; fourth, no

.tendency, or a reduced tendency, to foul and form sludge upon thecathode surface in such manner that. it cannotbe readily removed; andfifth, such elements and such a balance of forces and properties thatits efficiency will remain unimpaired force. considerable period oftime, and use.

The solution which I-shall hereinafterset forth, and which has for itsprincipal active element a nitrate or nitrates, either alone or incombination with certain other substances, meets these conditions, andhas e'nabledme,

by actual test, to produce as good results with the last plate of a longseries, as with the first one, for example the same depth of etching inthe same length of time.

The present invention is correlated to and in most cases interchangeablewith the inventions set forth in my companion applications executed ofeven date herewith and my prior applications Serial Numbers 159,776,159,7 7 7 and 159,778, all filed April 4, 1917. The solution in thepresent case has for its principal active element a nitrate or nitratesalone or in combination with certain other substances.

The class of metals with which this electrolyte is useful is very large,including all the metals specified in my prior applications abovereferred to, and many others. The metals most commonly employed in theengraving art are copper, brass, steel, and zinc, and the plates areemployed for printing, stamping, and for other purposes. In addition tothe engraving of steel printing plates both in relief and intaglio, themanufacture of steel dies and plates for stamping metals is,-in itself,very important, and by my process, and with my solutions, I can producesuch dies and plates in much less time, and with much less expense, thanwhere they are cut by hand according to the practice prior to thisinvention. Where the plates are to be employed forprinting, my

invention is specially important at the present time, because of thescarcity of high grade paper, and the necessity for having perfectprinting plates in order to produce satisfactory results on the cheapgrade of paper now commonly employed, because of such scarcity.Electrolytes are prepared, for the greatest efficiency and economy, forthe particular metals to be etched. Wherever practicable,

a combination is. used in which the plate to be etched is kept cleanWithout Wipin This is especially requisite in very delicate work, asfrequent wiping would tend to injure the material of the image. Incoarse work, this is relatively immaterial, and an electrolyte involvingwiping of the plate may easily be used, and-would-be used where itischeaper 'to prepare, or produces a speedier action.

The cleanliness of the cathode is next preferable, as involving lesslabor in keeplng clean, or as rendermg that portion of my apparatushaving movable brushes unnecessary, with a consequent saving in powerused thereby. For the reasons stated, some of my formulae do not giveboth a clean cathode and a clean anode.

The various use of nitrates, oxalates,

. chlorids and sulfates, with or without acids,

is in some instances to secure anode or cathode plate cleanliness orboth, and to obtain electrolytes which shall form the best chemicalcombinations in themselves and v without acid density. The value of thislast is obvious,

particularly where one dynamo or battery set is employed to supplycurrent for the etching of different metals in separate tanks withoutthe employment of resistance.

An acid condition is desirable in all electrolytes to give stability tothe same and to increasc the conductivity. If the constituent salts donot render the electrolyte acid or sufliciently acid for these purposes,an acid should be added. Some excellent electrolytes would promptlyseparate under electrolysis and promptly become useless were it not forthe additionof the acid, Even if this does not occur the life of theelectrolyte is shorter and its conductivity less. Further in many casesthe presence of an acid prevents precipitations in the electrolyte or onthe cathode or on the anode or performs two or all of these functions.

In some combinations where the ordinary acids do not keep thecathode orthe anode clean orprevent precipitations in the bath, this may in someinstances be partly or wholly accomplished by the addition of a chromiumsalt, or by what is generally termed chromic acid (usually potassiumdichromate solution acted upon by sulfuric acid), although the actionherein stated does not depend onthe sulfuric acid in the chromic acid asthat might independently be present in or added to the electrolyte underthe head of acids. The chromium salts are also employed on account. oftheir tendency to produce a smooth surface in the anode where it isfound that ordinarily the surface is rough, smoothnessof the anode beingusually a desirablefeature.

Specifically stated, the solution to be claimed herein consistsessentially of one or more of the nitrates of aluminum, ammonium,barium, cadmium, calcium, cobalt, I copper, iron, lead,lithium,magnesium, manganese, nickel, potassium, sodium, strontium, tin,uranium and zinc.

l/Vhile the essence of the invention is the use of a suitable nitrate, Imay and do employ more than one, in combination, when required, but itis obvious that only those which will properly mix or combine can besin'iultaneously employed.

With the nitrates, I may combine a sulfate, an oxalate, a chlorid, or achromium salt, or any combination thereof, with or without the additionof an acid. 1 may also employ. as an additional element, a smallquantity of a perchlorid, such as the perchlorid or iron, containing anexcess of acid.

' Muriatic acid C. P

This may be used in lieu of one or more of the foregoing nitrates, andin such case, no other acid is usually necessary. The principal functionof the separate acid, if

radded, is to increase the conductivity and prevent decrease in currentdensity and tends in most cases to keep the face of the plate clean andto prevent disintegration of the solution.

As an example of a solution in which a nitrate and an acid are employed,I mav give the following:

Calcium nitrate 240 grains. Water 4 oz. a oz.

As an example of a solution in which a nitrate and a chlorid with anacid are employed, I may give the following:

Aluminum nitrate 180 grains.

l/Vater 2oz. Solution of ammonium chlorid in water 15 Baum Sulfuric acidC. P

As an example of a solution contalnlng a nitrate and a sulfate with anacid, I may give the following:

2 oz. l; oz.

Iron nitrate -l Nickel'sulfate 120 grains.

Water 4oz. Sulfuric acid C. P loz.

As an example of a nitrate and an oxalate 5 with an acid, I may give thefollowing:

Cobalt nitrate 60 grains. Water 202. Mix following and add iron oxalate30 grains. 40 ,Water Q. 2oz; Nitric acid C. P oz.

I As an example of a nitrate, a sulfate and a chlorid with an acid, Imay give the following: I

Iron nitrate 120 grains. Nickel sulfate; 120grains. Iron (ferric)chlorid 120 grains. l/Vatei 602.

Sulfuric acid '-1-oz.

As an example of a nitrate, a chlorid and an oxalate with an acid, I maygive the following As an example of a nitrate,a sulfate and 120 grains.-

a chlorid with an acid,'I may give the following:

Ammonium nitrate 120 grains. Ammonium sulfate 120 grains. Water 2 oz.

Solution ammonium chlorid (in water) to test 15 B'aum 1 oz.

Mix and add the following: Iron oxalate 30 grains. Water 1 oz.

As an example of a nitrate, an oxalate and a chromium salt with an mad,I' may give It is to be noted that in the claims where I mention achlorid, an oxalate or a sulfate, or a combination of any of theseWithout mentioning a particular metal, I include in that term one ormore of the salts from the same acid, that is one or more acetates, oneor more borates, etc.

Having thus described my invention what I claim and desire to secure byLetters Pat.- ent is- 1. In electrolytic etchin'g, an anodeearrying aresistant image to be etched, in combination with an electrolytecomprising one or more of the nitrates of aluminum, ammonium, barium,cadmium, calcium, cobalt, copper, iron, lead, lithium, magnesium,manganese, nickel, potassium, sodium, strontium, tin, uranium and zinc.

. 2. In electrolytic etching, an anode carrying a resistant image to beetched, in combination with an electrolyte comprising one or more of thenitrates of aluminum, ammonium, barium, cadmium, calcium, cobalt,copper, ir'on, lead, lithium, magnesium, manganese, nickel, potassium,sodium, strontium, tin, uranium and zinc, with an acid.

3. In electrolyte etching, an anode carrying a resistant image to beetched, in combination with an electrolyte comprising one or 115 more ofthe nitrates of aluminum, ammonium, barium, cadmium, calcium, cobalt,copper, iron, lead, lithium, magnesium, manganese, nickel, potassium,sodium, strontium, tin, uranium and zinc, with a chlorid and an acid.

4. In electrolytic etching, an anode carrying a resistant image to beetched, in combination with an electrolyte comprising one or more of thenitrates of aluminum, ammonium, barium, cadmium, calcium, cobalt,copper, iron, lead, lithium, magnesium, manganese, nickel, potassium,sodium strontium, tin, uranium, and zinc, with a chlorid, a sulfate andan acid.

In electrolytic etching, an anode carrying a resistant image to beetched, in combination with an electrolyte comprising one or more of thenitrates of aluminum, ammonium, barium, cadmium, calcium, cobalt,copper, iron, lead, lithium, magnesium, manganese, nickel, potassium,sodium, strontium, tin, uranium, and zinc, with a chlorid, a sulfate, anoxalate and an acid.

(3. In electrolytic etching, an anode carrying a resistant image to beetched, in'combination with an electrolyte for electrolytic etchingcomprising one or more of the nitrates of aluminum, ammonium, loarium,cadmium, calcium, cobalt, copper, iron, lead, lithium, magnesium,manganese, nickel, potassium, sodium, strontium, tin,

'uraniun'i and zinc, with an acid and one or more salts other than anacetate, box-ate, nitrate or tartrate.

In testimony whereof I affix my signature. JOSEPH H. WEEKS.

